It’s worth remembering that Putin had to leave the presidency in the first place because Russia’s 1993 Constitution bans presidents from serving more than two consecutive terms. Therefore, he turned the office over to his handpicked successor Dmitri Medvedev, who will now become prime minister after Putin’s nearly inevitable victory in the 2012 election, from which most opposition parties are effectively excluded from participating. Putin’s return to the presidency cuts off any hope that the Russian government will continue Medvedev’s moves towards modest political and economic liberalization.

The whole sorry situation highlights the wisdom of the US Constitution’s 22nd Amendment, which not only bars presidents from serving more than two consecutive terms, but also forbids two-term presidents from ever holding the office again in the future. That prevents American presidents from pulling off the trick that Putin used with Medvedev – leaving a loyal flunky in power for four years and then returning to office. It thereby makes it much harder for any one man to consolidate dictatorial dominance.

Obviously, there are many other differences between the US and Russian political systems that make authoritarianism a lesser danger in the former. Nonetheless, the power of the modern presidency is great enough that a popular leader who could serve indefinitely might consolidate enormous power and gradually undermine democracy. At the state level, term-limited governors who are allowed to return to office later have sometimes used relatives or friends as placeholders for a term until they can return to power. George Wallace, for example, used his wife Lurleen.There is no reason why a president could not adopt the same tactic.

In the Russian case, Medvedev might well have taken a more liberal and independent line if he knew that Putin could not come back. Even if Medvedev did not do so, other Russian political elites might have acted differently if not for the spectre of Putin’s return hanging over them. At the very least, it would have been harder for Putin – or anyone else – to concentrate power in the hands of one man and the narrow clique surrounding him. In theory, Putin might have been able to just ignore the Constitution in 2008 and stay in power anyway. But doing so would have undermined his legitimacy with the West, and probably at home as well. That’s why he chose to leave office in 2008 rather than stay on illegally.

Despite Putin’s imminent return to the presidency, his power is not completely secure. Even with government control of much of the media, public opinion is starting to turn against him and especially his government. If the price of oil falls, Russia’s oil-dependent economy will decline with it, and other elites might then find it in their interest to turn against the regime. Putin’s government is not nearly as brutal and oppressive as its Soviet predecessor, and there are still many active opposition groups who could take advantage of the government’s difficulties. For the time being, however, Putin has successfully consolidated his authoritarian regime. And his ability to return to the presidency after a four year hiatus is one of the reasons why.